A flight controller determines that an airplane is 20.0 mi south of him. Half an hour later,

Question:

A flight controller determines that an airplane is 20.0 mi south of him. Half an hour later, the same plane is 35.0 mi northwest of him.
(a) The general direction of the airplane’s velocity is (1) east of south, (2) north of west, (3) north of east, (4) west of south.
(b) If the plane is flying with constant velocity, what is its velocity during this time?